In passenger aircraft, the Electro-Hydraulic Servo Actuators (EHSA) are still the leading technology used for primary and secondary flight controls. Their Maintenance, Repairing and Overall procedures (MRO) are predominantly manual and high-priced. Therefore, Lufthansa Technik has developed an innovative and automatic testing procedure, with the purpose to reduce the MRO cost and improve the diagnostic accuracy. The servo actuator is commanded by means of a modular excitation signal in order to extract significant features from the unit response. Then, the analysis of the feature points out the faulty components inside the unit. The present thesis introduces new troubleshooting techniques by the extraction of additional health features concerning the elevator servo actuator.